Method of manufacturing image sensor for reducing crosstalk characteristic

ABSTRACT

An image sensor includes a plurality of photoelectric detectors, a plurality of color filters, and at least one pixel isolation region between adjacent ones of the photoelectric detectors. The color filters include a white color filter, and the color filters correspond to respective ones of the photoelectric detectors. The at least one pixel isolation region serves to physically and at least partially optically separate the photoelectric detectors from one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application based on pending application Ser. No.14/814,829 filed Jul. 31, 2015, the entire contents of which is herebyincorporated by reference.

Korean Patent Application No. 10-2014-0099137, filed on Aug. 1, 2014,entitled, “Image Sensor for Reducing Crosstalk Characteristic and Methodof Manufacturing the Same,” is incorporated by reference herein in itsentirety.

BACKGROUND

1. Field

One or more embodiments described herein relate to an image sensor and amethod for manufacturing an image sensor.

2. Description of the Related Art

An image sensor converts an optical image into an electrical signal. Asthe computer and communication industries continue to develop, thedemand for image sensors with improved performance increases in variousfields, including but not limited to digital cameras, camcorders,personal communication systems, game devices, security cameras, medicalmicro-cameras, and robotics,

An image sensor generally includes a pixel array, where each pixel has aphoto diode that performs a photoelectric conversion function. Eachpixel may also have a color filter to filter light of a specificwavelength region. In these and other types of image sensors, opticalcrosstalk may occur, for example, based on a spectral difference betweenadjacent pixels.

SUMMARY

In accordance with one or more embodiment, an image sensor includes asemiconductor substrate; a plurality of photoelectric detectors; aplurality of color filters spaced from the semiconductor substrate; andat least one pixel isolation region having a predetermined depth,wherein the at least one pixel isolation region is between adjacent onesof the photoelectric detectors, wherein the color filters include awhite color filter, and wherein the color filters correspond torespective ones of the photoelectric detectors.

The color filters may include one of a green filter, a red filter, or ablue filter. The at least one pixel isolation region may extend betweenthe semiconductor substrate a layer including the color filters, and theat least one pixel isolation region may contact the semiconductorsubstrate. The at least one pixel isolation region may include aninsulating material. The at least one pixel isolation region may includea bottom at a higher level than a bottom of at least one of thephotoelectric detectors.

In accordance with another embodiment, an image sensor includes asemiconductor substrate; at least one pixel isolation region in a trenchover the semiconductor substrate; a plurality of photoelectric detectorsseparated from each other by the at least one pixel isolation region; ananti-reflection layer on the at least one pixel isolation region and thephotoelectric detectors; a plurality of color filters on theanti-reflection layer; and a plurality of microlenses on the colorfilters, wherein the color filters include a white filter.

The at least one pixel isolation region may be between the semiconductorsubstrate and a layer including the color filters, and the at least onepixel isolation region may contact the semiconductor substrate. The atleast one pixel isolation region may include silicon oxide. The at leastone pixel isolation region may include an oxide of a high permittivity.

The at least one pixel isolation layer may include an insulating layersurrounding a conductive metal layer. The at least one pixel isolationregion may extend in a direction toward the semiconductor substrate, anda bottom of the at least one pixel isolation region may be at a higherlevel than a bottom of one or more of the photoelectric detectors. Arefractive index of the at least one pixel isolation region may bedifferent from a refractive index of one or more of the photoelectricdetectors. The color filters may include a green filter, a red filter,or a blue filter. The color filters may correspond to the photoelectricdetectors, respectively. The microlenses may correspond to the colorfilters, respectively.

In accordance with another embodiment, a method of manufacturing animage sensor includes providing a semiconductor substrate; forming aphotoelectric detector layer on the semiconductor substrate; forming atleast one trench in the photoelectric detector layer to a predetermineddepth; filling the at least one trench with an insulating material toform at least one isolation region; forming a color filter layer on thephotoelectric detector layer and the at least one isolation region, thecolor filter layer including a white filter and at least one of a redfilter, a green filter, or a blue filter; and forming microlenses on thecolor filter layer.

Forming the at least one trench may include etching the photoelectricdetector layer in a direction of the semiconductor substrate. Formingthe at least one trench may include etching the photoelectric detectorlayer so that a height of the at least one trench is substantially equalto a height of the photoelectric detector layer and so that a surface ofthe semiconductor substrate is exposed. Forming the at least one trenchmay include etching the photoelectric detector layer so that a bottom ofthe at least one trench is higher than a bottom of the photoelectricdetector layer. The at least one trench may be between adjacentphotoelectric detectors in the photoelectric detector layer. Theinsulating material may have a refractive index different from arefractive index of the photoelectric detector layer.

The method may include forming an anti-reflection layer before formingthe color filter layer. The method may include forming a polysiliconlayer inside the at least one trench. The microlenses may correspond tothe white filter and at least one of the red filter, the green filter,or the blue filter, respectively. The white filter and at least one ofthe red filter, green filter, and blue filter may correspond to thephotoelectric detectors, respectively.

In accordance with another embodiment, an image sensor includes a firstpixel; a second pixel; and an isolation region between the first andsecond pixels, wherein each of the first and second pixels includes aphotodetector and a color filter, the isolation region under the colorfilter and extending along and optically separating the photodetectorsof the first and second pixels. The isolation region may include a firstsurface to reflect incident light in a direction toward thephotodetector of the first pixel and a second surface to reflectincident light in a direction toward the photodetector of the secondpixel.

The image sensor may include a first color filter and a second colorfilter, wherein the first color filter may correspond to thephotodetector of the first pixel and the second color filter maycorrespond to the photodetector of the second pixel, and wherein thefirst color filter may be a white color filter. The isolation region andthe photodetectors of the first and second pixels may have substantiallya same height. The isolation region may have a first length, thephotodetectors of the first and second pixels may have a second length,and the first length may be less than the second length.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail exemplary embodiments with reference to the attached drawingsin which:

FIG. 1 illustrates one type of image sensor;

FIGS. 2A and 2B illustrate examples of color filter arrays;

FIG. 3 illustrates an embodiment of a unit pixel;

FIG. 4 illustrates a pixel circuit having a 4-transistor (4T) structure;

FIG. 5 illustrates an embodiment of a backside-illuminated image sensor;

FIGS. 6A to 6E illustrate stages in an embodiment of a method formanufacturing the image sensor in FIG. 5;

FIG. 7 illustrates another embodiment of an image sensor;

FIG. 8 illustrates another embodiment of an image sensor;

FIG. 9 illustrates another embodiment of an image sensor;

FIG. 10 illustrates an embodiment of a pixel circuit with a 4T-2 sharedstructure;

FIG. 11 illustrates an embodiment of a pixel circuit with a 3-transistorstructure;

FIGS. 12A to 12C illustrate embodiments of multimedia devices; and

FIG. 13 illustrates an embodiment of a processor-based system.

DETAILED DESCRIPTION

Example embodiments are described more fully hereinafter with referenceto the accompanying drawings; however, they may be embodied in differentforms and should not be construed as limited to the embodiments setforth herein. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully conveyexemplary implementations to those skilled in the art.

In the drawings, the dimensions of layers and regions may be exaggeratedfor clarity of illustration. It will also be understood that when alayer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings. In detailed descriptions of theexemplary embodiments, detailed descriptions of well-knownconfigurations unrelated to the exemplary embodiments will be omitted.In this specification, when reference numerals are assigned tocomponents of each drawing, it should be noted that, although the samecomponents are illustrated in different drawings, the same numerals areassigned as much as possible.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be teamed asecond element, and similarly, a second element could be termed a firstelement.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion,that is, “between” versus “directly between,” adjacent” versus “directlyadjacent,” etc.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of claim scope. Asused herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein are to be interpreted as is customary in the art towhich the embodiments belong. It will be further understood that termsin common usage should also be interpreted as is customary in therelevant art and not in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 illustrates one type of image sensor 10 which includes a timingcontroller (TCON) 1, a row driver 2, a pixel array 3, a correlateddouble sampler (CDS) 4, a ramp generator 5, and an output buffer 6.

The TCON 1 generates control signals for driving the pixel array 3 andprovides the generated control signals to the row driver 2 and the CDS4. For example, the TCON 1 may receive image data and various controlsignals from an external source and control operations of the row driver2 and the CDS 4.

The row driver 2 provides pixel selection-related signals to controldriving of the pixel array 3. The row driver 2 provides a control signalwhich, for example, may select a row (e.g., a row control signal) fordecoding or which is based on a decoded address signal. At least one rowof the pixel array 3 may be selected by the row control signal.

The pixel array 3 may include pixels which are connected to a pluralityof rows and columns in a matrix form. Each pixel may include, forexample, a red pixel for electrically converting the light in a redspectral region, a green pixel for electrically converting the light ina green spectral region, a blue pixel for electrically converting thelight in a blue spectral region, or a white pixel capable ofelectrically converting all spectra in the visible light region. Whenthe pixel array 3 uses a white pixel, the formation of a highlysensitive display is possible.

In one embodiment, a unit pixel may include four color filters, e.g.,white, red, blue, and green filters. For example, each of the colorfilters for transmitting the light in a specific spectral region may bearranged on an upper part of each pixel. Each pixel includes a photodetector. The pixel array 3 may electrically convert an optical signalin response to a control of the TCON 1 and the row driver 2, and theelectrically converted signal may be displayed.

The unit pixel may be arranged in a 2×2 array pattern or a differentpattern. For example, the unit pixel may include a 4×4 array form, a 6×6array form, or an array form in which a green pixel is removed.Arrangements such as illustrated in FIGS. 2A and 2B may include variousarrangements of filters to increase sensitivity of a display.

FIG. 2A illustrates a color filter array 50 which includes a pluralityof color filters R, G, W, and B. In the color filter array 50, thelocation and arrangement of the color filters may be changed toappropriate locations, while maintaining a basic pattern 60. However,sizes of unit areas in which the color filters R, G, W, and B areimplemented are substantially the same.

FIG. 2B illustrates a color filter array 50 that has a 4×4 array, wherethe white filter W instead of the green filter G may be at anappropriate location or the white filter W may be appropriately at onlya necessary location. For example, the color filter array 50 may beconfigured in various ways depending on the intent of a designer or arequired specification of a panel.

The CDS 4 receives an electrical signal formed on the pixel array 3through a vertical signal line and performs a sampling operation ormaintains the electrical signal. The CDS 4 performs double sampling of aspecific noise level and a signal level in the generated electricalsignal. As a result, a fine voltage is output corresponding to adifference between the noise level and the signal level.

The ramp generator 5 generates a reference voltage (e.g., a rampvoltage) used in the CDS 4 and provides the reference voltage. Forexample, the ramp generator 5 may be an integrator and may generate aramp voltage of a waveform having a level that is changed to an inclinedlevel or a stepped level as time passes. The output buffer 6 receivesthe double-sampled signal from the CDS 4.

FIG. 3 illustrates an embodiment of a unit pixel, which, for example,may be included in FIG. 1. Referring FIG. 3, the unit pixel includes aphoto-detecting device layer 14, an anti-reflection layer 13, a colorfilter layer 12, and a microlens layer 11.

The unit pixel may be included in a backside illuminated image sensor,in which incident light is illuminated through a back surface of asemiconductor substrate and is photoelectrically converted so that thepixels have an improved light receiving efficiency and lightsensitivity.

First, the photo-detecting device layer 14 may include a materialcapable of detecting light. For example, formation of thephoto-detecting device layer 14 may be performed through an ionimplantation process with an N-type impurity. When the photo-detectingdevice layer 14 is formed, the ion implantation process is performed ona region, which may be a lower part of each filter, with a differentdoping concentration so as to form a potential barrier.

The anti-reflection layer 13 is formed on the photo-detecting devicelayer 14. For example, the anti-reflection layer 13 may include asilicon oxide based material. The anti-reflection layer 13 may be orinclude a layer having an anti-reflection function using, for example,SiON, SiC, SiCN, or SiCO. A caption layer to protect the substrate maybe included with or instead of the anti-reflection layer 13.

The color filter layer 12 is formed on the anti-reflection layer 13. Thecolor filter layer 12 has an array structure including, for example, ablue filter, a green filter, a red filter, and a white filter. The colorfilter layer 12 may be formed, for example, by coating and patterning amaterial of forming a color filter using an appropriate mask. A dyedphotoresist may be mainly used as the material of forming a colorfilter.

Such a color filter layer 12 includes four filters of red, green, blue,and white. For example, the white filter may be formed by a transparentplanarizing layer so that all wavelengths in the visible light region(e.g., in a red region, a green region, and a blue region) aretransmitted. Alternatively, the white filter may be formed by a materialin which a pigment is removed from a photoresist material, or may not beformed by any material in a region for a white filter by forming anopening. However, since the latter case may cause expansion of regionsof adjacent pixels, caution is needed.

The microlens layer 11 may be formed on the color filter layer 12, andmay use a photoresist having an excellent light transmission. Themicrolens layer 11 is arranged and formed at a location corresponding tothe color filter layer 12. For example, the microlens layer 11 is formedby coating and patterning a photoresist for a microlens. Then, themicrolens layer 11 having a hemispherical dome form may be formed whenperforming a reflow process using a thermal process. An over-coatinglayer may be interposed between the color filter layer 12 and themicrolens layer 11.

In the process of forming the unit pixel of the image sensor, thephoto-detecting device layer 14 is formed, a potential barrier is formedin a region corresponding to a lower part of each filter, and then thefilters are distinguished. For example, device isolation between photodiodes may be performed based on a doping profile. However, in the caseof a white filter, since a spectral range thereof is relatively widerthan those of the other filters and light is incident on an adjacentpixel, a crosstalk phenomenon between the adjacent pixels may occur.

FIG. 4 illustrates a pixel circuit having a 4-transistor (4T) structure.The pixel includes a photo-detecting device PD and four transistors N1,N2, N3, and N4.

The photo-detecting device PD photoelectrically converts incident lightto a number of electrons corresponding to a quantity of the light. Thephoto-detecting device PD may include at least one of a photo diode, aphoto transistor, a photo gate, a pinned photo diode (PPD), or acombination thereof.

A transfer transistor N2 is electrically connected between thephoto-detecting device PD and an output node A which is a floatingdiffusion region. When a drive signal VT is applied, the transfertransistor N2 turns on to transfer the electrons photoelectricallyconverted from the photo-detecting device PD, which is a photoelectricconversion device, to the output node A.

A reset transistor N1 is electrically connected between a pixel voltageVDD and the output node A. The reset transistor N1 is controlled by areset signal RST to reset an electric potential of the output node Abased on a level of the pixel voltage VDD.

An amplifying transistor N3 is electrically connected to the output nodeA. The amplifying transistor N3 may be, for example, a source followerwith a selection transistor N4.

The selection transistor N4 is controlled by a selection signal RSEL andmay be electrically connected, for example, between a correlated doublesampling (CDS) circuit and the amplifying transistor N3. When theselection signal RSEL is activated, the selection transistor N4 may beturned on, and the electric potential of the output node A may beamplified and output through the amplifying transistor N3.

An analog voltage output from each pixel in the pixel array is convertedinto a digital value and processed according to a subsequent operation.For example, an analog-to-digital (A/D) conversion may be performed bytwo read operations on a row. During a first read operation, the resetlevel of the pixel is read and then the A/D conversion is performed. Avariation may occur for each unit pixel at the reset level. During asecond read operation, an actual signal, which is photoelectricallyconverted, is read from the pixel and then the A/D conversion isperformed. In this case, since a variation may also occur for each unitpixel, a CDS may be performed. As described above, a signal is convertedto a digital signal and provided as a final output through a subsequentcircuit, for example, the output buffer 6 (see FIG. 1).

In one type of image sensor, light passes through a lens to illuminate aphotoelectric conversion device formed on a multilayered wiring layer.The photoelectric conversion device detects light which is transmittedbetween or among the wiring layers. However, the amount of incidentlight which actually reaches the photoelectric conversion device may notbe enough, because a layout which includes the multilayered wiring layerserves as a obstacle that attenuates light transmission to thephotoelectric conversion device. For example, since an aperture ratiowith respect to the photoelectric conversion device is reduced by thelayout having the multilayered wiring layer, the amount of lightincident on the photoelectric conversion device is significantlyreduced. Therefore, sensitivity may be degraded.

FIG. 5 illustrates an embodiment of a backside illuminated image sensor(BIS) 100. The BIS 100 formed on the backside of a semiconductorsubstrate 101. In operation, light illuminates from the backside of thesemiconductor substrate 101 (e.g., opposite a wiring unit), and then thephotoelectric conversion device receives the light. Thus, an effectiveaperture ratio may be increased and sensitivity may be significantlyimproved, without using a layout having a multilayered wiring layerwhich serves as an obstacle in the aforementioned image sensor.

Referring to FIG. 5, the BIS 100 includes the semiconductor substrate101, photoelectric detecting devices 102, pixel isolation regions 103,an anti-reflection layer 104, color filters 105, and microlenses 106. Inthis embodiment, the photoelectric detecting devices 102 are defined (orpartitioned) by the pixel isolation regions 103, and are provided underthe plurality of color filters 105 including a white filter W,respectively. Thus, an optical crosstalk phenomenon between adjacentpixels may be reduced.

The semiconductor substrate 101 may be, for example, a silicon wafer, asilicon on insulator (SOI) substrate, or a semiconductor epitaxiallayer. Although the semiconductor substrate 101 is exemplified forconvenience of description, a plurality of transistors (see, e.g., thetransfer transistor N2, the reset transistor N1, the amplifyingtransistor N3, and the selection transistor N4 in FIG. 4) may beprovided. Further, the semiconductor substrate 101 may include a metalwiring layer of a conductive material. For example, the semiconductorsubstrate 101 may be provided as a resultant structure including thedescribed above plurality of transistors and the metal wiring layer.

The photoelectric detecting devices 102 may be provided on the backsideof the semiconductor substrate 101 described above. Each of thephotoelectric detecting devices 102 may be defined by at least one ofthe pixel isolation regions 103. The photoelectric detecting device 102may include, for example, a photo diode, a photo transistor, a photogate, a PPD, or a combination thereof. In one embodiment, thephotoelectric detecting device 102 may correspond to the photo-detectingdevice PD in FIG. 4.

Each of the pixel isolation regions 103 may be included in a layerformed using a deep trench isolation (DTI) process, so that thephotoelectric detecting devices 102 are spaced apart from each other,e.g., along the x and y axes. For example, a trench formed to have adepth which is substantially the same as a height of the photoelectricdetecting device(s) 102 is filled (e.g., along the z axis) and, thus,corresponding ones of the pixel isolation regions 103 may be formed. Thepixel isolation regions 103 isolate the light that targets correspondingones of the photoelectric detecting devices 102. Thus, dispersion of thelight to adjacent photoelectric detecting devices 102 may be minimized.

Therefore, according to one embodiment, the photoelectric detectingdevices 102 corresponding to the pixel regions are physically spacedapart and distinguished from each other by the pixel isolation regions103. As a result, optical and electrical crosstalk phenomena caused by aspectral difference between the filters of the pixels may be reduced.

The anti-reflection layer 104 may be formed on the pixel isolation layer103 and the photoelectric detecting devices 102.

The color filters 105 are formed to correspond to the photoelectricdetecting devices 102, respectively. The color filters 105 may be, forexample, red, white, green, and blue filters. The color filters maycorrespond to a different combination of colors in another embodiment.

The microlenses 106 may be formed on upper surfaces of the color filters105, respectively. For example, the microlenses 106 may be arranged andformed on locations corresponding to the color filters 105,respectively.

FIGS. 6A to 6E are cross-sectional views of stages in an embodiment of amethod for manufacturing an image sensor such as illustrated in FIG. 5.Referring to FIG. 6A, a photoelectric detecting device layer 102 a maybe formed on a semiconductor substrate 101 including a front side. Inone embodiment, after the front side of the semiconductor substrate 101is completed, the photoelectric detecting device layer 102 a may beformed, for example, by implanting N-type impurity ions onto a backsideof the semiconductor substrate 101. Alternatively, the photoelectricdetecting device layer 102 a may be formed by implanting a plurality ofP-type and N-type ions. The photoelectric detecting device layer 102 ais therefore formed of a material that receives and detects light.

Referring to FIG. 6B, a predetermined number of deep trenches 103 a areformed in the photoelectric detecting device layer 102 a. For example,predetermined regions of the photoelectric detecting device layer 102 aare etched, and then the deep trenches 103 a that expose an uppersurface of the semiconductor substrate 101 are formed.

The distance between the deep trenches 103 a may be determined within apredetermined range. The predetermined range may be one in whichsufficient light may be incident through color filters 105 (see FIG. 5)and photoelectric detecting devices 102 (see FIG. 5). Further, the depthof the deep trench 103 a may be substantially the same as a height ofthe photoelectric detecting device layer 102 a. For example, the depthmay be 1 μm or more. In one embodiment, the depth of the deep trench 103a may be in a range of 2 to 3 μm depending, for example, on the product.

Referring to FIG. 6C, the deep trenches 103 a (see FIG. 6B) are filledwith insulating material and then pixel isolation regions 103 areformed. Thus, the photoelectric detecting devices 102 may be separatedfrom each other. Further, each of the completed photoelectric detectingdevices 102 may receive and detect light of a predetermined spectrum.

The insulating material may be, for example, an insulating materialhaving a different refractive index from the photoelectric detectingdevice 102. In one embodiment, the insulating material that forms aninside of the pixel isolation regions 103 may include silicon oxide.

The pixel isolation region 103 not only may physically separate thephotoelectric detecting devices 102, but also may reflect light, so thatlight incident on each corresponding pixel is not incident on anadjacent pixel. Because regions of the pixels are separated and spacedby the pixel isolation regions 103, the optical crosstalk phenomenon maybe reduced. The pixel isolation regions 103 may also be referred to aslight barrier regions, in terms of suppressing the crosstalk phenomenonby reflecting the incident light.

Referring to FIG. 6D, an anti-reflection layer 104 is formed on theresultant structure illustrated in FIG. 6C. The anti-reflection layer104 may include a material performing an anti-reflection function. Forexample, the anti-reflection layer 104 may include a silicon basedmaterial, e.g., SiON, SiC, SiCN, or SiCO. In FIG. 6D, theanti-reflection layer 104 is illustrated as a single layer.

In another embodiment, the anti-reflection layer 104 includes multiplelayers in which materials having different refractive indexes arestacked. For example, the anti-reflection layer 104 may be formed as astacked layer (e.g., an oxide layer/a nitride layer or a nitridelayer/an oxide layer) in which the oxide layer and the nitride layer arestacked. In another embodiment, the anti-reflection layer 104 may beformed from a stacked layer including at least one carbon-based layer,e.g., an oxide layer/SiC layer or an SiC layer/an oxide layer.

The oxide layer may include, for example, a borophosphosilicate glass(BPSG) layer, a phosphosilicate glass (PSG) layer, a borosilicate glass(BSG) layer, an un-doped silicate glass (USG) layer, a tetra ethyl orthosilicate (TEOS) layer, or a high density plasma (HDP) layer. The nitridelayer may include, for example, a silicon nitride layer (Si_(x)N_(y),where x and y are natural numbers) or a silicon oxynitride layer(Si_(x)O_(y)N_(z), where x, y, and z are natural numbers).

Referring to FIG. 6E, the color filters 105 are formed on the resultantstructure shown in FIG. 6D. The color filters 105 include a plurality offilters. The plurality of filters may include, for example, a red filterR, a white filter W, a green filet G, and a blue filter B. The whitefilter W may be included in the color filters 105, for example, toincrease sensitivity of image quality during display.

When the red filter R is referred to as a filter of a first type, thefilter of the first type may be replaced by a cyan filter, a yellowfilter, or a magenta filter.

When the green filter G is referred to as a filter of a second type, thefilter of the second type may be replaced by a cyan filter, a yellowfilter, or a magenta filter.

When the blue filter B is referred to as a filter of a third type, thefilter of the third type may be replaced by a cyan filter, a yellowfilter, or a magenta filter.

When the white filter W is referred to as a filter of a fourth type, thefilter of the fourth type may be implemented by a transparent filter ora filter that may block infrared light. Although the white filter W isformed by the transparent filter to transmit all of the light in thevisible light region, the white filter may be different constructed inother embodiments. In one embodiment, the white filter may transmit apredetermined number of light colors less than all light colors.

Referring again to FIG. 5, the microlenses 106 are formed on the colorfilters 105. The microlens 106 may use a photo resist having excellentlight transmission. The microlenses 106 are arranged and formed atlocations corresponding to respective ones of the color filters 105. Forexample, material of the microlens 106 is coated with a photo resist andthen patterned. Then, the microlens 106 having a hemispherical dome formmay be formed when performing a reflow process using a thermal process.

The microlens 106 may be formed on the backside of the semiconductorsubstrate 101. Thus, a BIS may be formed in which light illuminates thebackside of the semiconductor substrate 101 and the light is incident onthe photoelectric detecting device 102 serving as a light receivingpart. The BIS may serve to reduce occurrence of the optical crosstalkphenomenon between adjacent pixels. The pixel isolation regions 103 maybe formed using another method than described above.

FIG. 7 illustrates another embodiment of an image sensor 1100 includingpixel isolation regions 107. Referring to FIG. 7, the structure andfunction of the image sensor 1100 may be similar to those of the imagesensor 100 in FIG. 5, but the process for forming the pixel isolationregions may be different.

In accordance with this embodiment, the image sensor 1100 includes thesemiconductor substrate 101, photoelectric detecting devices 102, pixelisolation regions 107, anti-reflection layer 104, color filters 105, andmicrolenses 106.

The pixel isolation regions 107 may be formed by a DTI process, so thatthe photoelectric detecting devices 102 are spaced apart from eachother. In this case, the pixel isolation regions 107 may be formed byfilling a trench to a depth which is substantially the same as a heightof the photoelectric detecting device 102. The pixel isolation regions107 may be formed, for example, of a material having a permittivitygreater than that of silicon oxide (e.g., high-k) and a refractive indexless than the silicon oxide, e.g., hafnium oxide (HfO).

As a result, insulating characteristics of the pixel isolation regions107 is improved, and a difference between refractive indexes of thepixel isolation regions 107 and the photoelectric detecting device 102is increased. Thus, a total reflection condition is improved. Further,the process of forming the deep trench becomes easier, and thusformation of the pixel isolation regions 107 becomes simpler.

FIG. 8 illustrates another embodiment of an image sensor 1200 includingpixel isolation regions 108. Referring to FIG. 8, a structure and afunction of the image sensor 1200 may be similar to the image sensors100 and 1100 in FIGS. 5 and 7, but a process for forming the pixelisolation regions is different.

The pixel isolation regions 108 may be formed by a DTI process, so thatthe photoelectric detecting devices 102 are spaced apart from eachother. In this case, the pixel isolation regions 108 may be formed froma material filling a trench having a depth which is substantially thesame as a height of the photoelectric detecting device 102.

The pixel isolation regions 108 may include an insulating layer 108 aand a polysilicon layer 108 b interposed inside the insulating layer 108a. For example, a deep trench may be formed having a side wall (e.g.,insulating layer 108 a) with an oxide of approximately 50 Å thickness.The inside of the deep trench may be filled with the polysilicon layer108 b, and then the pixel isolation regions 108 may be formed from thepolysilicon layer 108 b. For example, the pixel isolation regions 108may be formed by the interposition of the polysilicon layer 108 b, whichis a conductive layer surrounded with the insulating layer 108 a. Thus,refractive index may be improved and interference between the pixels mayalso be reduced.

FIG. 9 illustrates another embodiment of an image sensor 1300 having astructure and a function similar to the image sensor 100 in FIG. 5, buta process for forming pixel isolation regions is different.

The image sensor 1300 includes the semiconductor substrate 101,photoelectric detecting devices 102, pixel isolation regions 109,anti-reflection layer 104, color filters 105, and microlenses 106.

The pixel isolation regions 109 may be formed by a trench isolationprocess, so that the photoelectric detecting devices 102 are spacedapart from each other in a predetermined region. In this case, the pixelisolation regions 109 may be formed to have a depth less than a heightof the photoelectric detecting devices 102. For example, the pixelisolation regions 109 may extend in a direction of the semiconductorsubstrate 101 from the color filter 105 by a predetermined depth, andthen may be formed to have a bottom at a higher level than thephotoelectric detecting devices 102.

For example, a trench having the predetermined depth may be formed inthe photoelectric detecting device layer 102 a (see FIG. 6A), aninsulating material may fill an inside of the trench, and then the pixelisolation regions 109 may be formed.

According to another embodiment, the photoelectric detecting devices 102may be etched to have an appropriate depth, so that light isappropriately incident thereon and is reflected. Thus, in thisembodiment, the photoelectric detecting devices 102 are not completelyisolated. As a result, etching stress with respect to the semiconductorsubstrate 101 may be reduced.

At the same time, since the pixel isolation regions 109 separate thephotoelectric detecting devices 102 in a predetermined region (e.g., aregion adjacent to light receiving related devices (e.g., the microlensand the color filter)) and physically block the light, optical crosstalkbetween the adjacent photoelectric detecting devices 102 may be reduced.

In the aforementioned embodiments, the photoelectric detecting devices102 corresponding to respective ones of the pixel regions are physicallyspaced apart and distinguished from each other by the pixel isolationregions 103, 107, 108, or 109. Thus, the optical and electricalcrosstalk phenomenon due to a spectral difference between the filters ofthe pixels may be reduced.

These or other embodiments may be applied to pixel circuits of variousstructures different from a 4T structure.

FIG. 10 illustrates an embodiment of a pixel circuit having a 4T-2shared pixel structure including pixels 21 and 31. Each of the pixels 21and 31 includes a photo diode and a transfer transistor coupled to thephoto diode. The remaining transistors in the pixels 21 and 31 arearranged in a shared structure.

Referring to FIG. 10, the first pixel 21 includes a first photo diodePD1, a first transfer transistor NM1, and a reset transistor NM2. Thesecond pixel 31 includes a second photo diode PD2, a second transfertransistor NM5, a source follower transistor NM3, and a selectiontransistor NM4.

In this structure, the first transfer transistor NM1 is connected to thefirst photo diode PD1 and controlled by a first drive signal TX1. Thereset transistor NM2 is between a floating diffusion region FD and apixel voltage VPIX, and controlled by a reset signal RST. The secondtransfer transistor NM5 is connected to the second photo diode PD2 andcontrolled by a second drive signal TX2. The source follower transistorNM3 is controlled by the floating diffusion region FD and constitutes asource follower with the selection transistor NM4. The selectiontransistor NM4 is controlled by a selection signal SEL and iselectrically connected to the source follower transistor NM3 to supplyan output voltage V_(OUT).

The pixels 21 and 31 are vertically arranged and may share the floatingdiffusion region FD. Although the pixels are connected to different rowsin this embodiment, signals photoelectrically converted from the photodiodes PD1 and PD2 may be transferred using the transfer transistors NM1and NM5, respectively. The selection transistor NM4, the source followertransistor NM3, and the reset transistor NM2 may be shared andcontrolled by a common signal. Since the number of the transistors ofthe pixel is decreased, the size of the pixel structure may be reduced.

FIG. 11 illustrates an embodiment of a pixel circuit having a3-transistor (3T) pixel structure. This pixel circuit excludes aselection transistor N4 (compare to FIG. 4). In this embodiment, theselection transistor N4 is replaced by controlling a reset transistor N2as a read voltage VRD.

Referring to FIG. 11, the pixel circuit having the 3T structure includesa photo diode PD1, a transfer transistor N1, a reset transistor N2, anda source follower transistor N3. The photo diode PD1 is electricallyconnected to the transfer transistor N1. The transfer transistor N1 iscontrolled by a drive signal TX, and transfers a signal, which isphotoelectrically converted from the photo diode PD1, to a floatingdiffusion region FD.

The reset transistor N2 is electrically connected to the floatingdiffusion region FD, and controlled by a reset signal RST. For example,the read voltage VRD of the reset transistor N2 is controlled by a rowto serve as a selection transistor when needed. The source followertransistor N3 amplifies an electric charge of the floating diffusionregion FD, and provides the amplified electric charge as an outputvoltage V_(OUT).

In the aforementioned embodiments of pixel circuits, the opticalcrosstalk phenomenon between the pixels may be reduced.

FIGS. 12A to 12C illustrate embodiments of multimedia devices which mayinclude image sensors in accordance with any of the aforementionedembodiments. FIG. 12A illustrates a smart phone 150, and FIG. 12Billustrates a smart TV 200. A high-resolution image sensor in accordancewith one or more of the aforementioned embodiments is mounted maymounted in the smart phone and a smart TV. An embodiment of a tablet PCmay also include one or more of the aforementioned embodiments of theimage sensor.

FIG. 12C illustrates a digital camera 300 including one or moreembodiments of the image sensor. Referring to FIG. 12C, the digitalcamera 300 may include an image sensor for capturing an image or amoving picture, and a display device for displaying an image or a movingpicture to be captured.

FIG. 13 illustrates an embodiment of an processor-based system 601including an image sensor according to one or more of the aforementionedembodiments. Referring to FIG. 13, the processor-based system 601 is asystem in which output images of a complementarymetal-oxide-semiconductor (CMOS) image sensor 610 are processed. Theprocessor-based system 601 may be, for example, a computer system, acamera, a scanner, a mechanized clock, a navigator, a video phone, asupervision system, an auto focusing system, a tracing system, a motionmonitoring system, or an image stabilization system, as well as othertypes of electronic devices or systems.

The processor-based system 601 (e.g., a computer system) may include acentral processing unit (CPU) 620 such as a microprocessor forcommunicating with an input/output device 630 through a bus 605. TheCMOS image sensor 610 may communicate with the processor-based system601 through the bus 605 or another communication link.

The processor-based system 601 may further include a RAM 640, a floppydisk drive 650 and/or a CD ROM drive 655, and a port 660, which cancommunicate with the CPU 620 through the bus 605. The port 660 may be aport in which a video card, a sound card, a memory card, a USB device,and the like are coupled, or data is exchanged with other systems. TheCMOS image sensor 610 may be integrated with a CPU, a digital signalprocessing (DSP) device, a microprocessor, and the like, and may befurther integrated with a memory. The CMOS image sensor 610 may also beintegrated on a chip separated from a processor in some cases.

In accordance with one or more of the aforementioned embodiments, aninsulating layer is interposed between photoelectric detecting devicesof an image sensor, so that the photoelectric detecting devices (e.g.,photo detectors) are physically separated from each other. As a result,optical crosstalk in the image sensor be reduced and high-resolutionimages may be provided. Additionally, a mobile device, and morespecifically, an image sensor and a memory system including the same,may include such an image sensor.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of skill in the art as of thefiling of the present application, features, characteristics, and/orelements described in connection with a particular embodiment may beused singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwiseindicated. Accordingly, it will be understood by those of skill in theart that various changes in form and details may be made withoutdeparting from the spirit and scope of the present invention as setforth in the following claims.

1.-15. (canceled)
 16. A method of manufacturing an image sensor,comprising: providing a semiconductor substrate; forming a photoelectricdetector layer on the semiconductor substrate; forming at least onetrench in the photoelectric detector layer to a predetermined depth;filling the at least one trench with an insulating material to form atleast one isolation region; forming a color filter layer on thephotoelectric detector layer and the at least one isolation region, thecolor filter layer including a white filter and at least one of a redfilter, a green filter, or a blue filter; and forming microlenses on thecolor filter layer.
 17. The method as claimed in claim 16, whereinforming the at least one trench includes etching the photoelectricdetector layer in a direction of the semiconductor substrate.
 18. Themethod as claimed in claim 17, wherein forming the at least one trenchincludes etching the photoelectric detector layer so that a height ofthe at least one trench is substantially equal to a height of thephotoelectric detector layer and so that a surface of the semiconductorsubstrate is exposed.
 19. The method as claimed in claim 17, whereinforming the at least one trench includes etching the photoelectricdetector layer so that a bottom of the at least one trench is higherthan a bottom of the photoelectric detector layer.
 20. The method asclaimed in claim 16, wherein the at least one trench is between adjacentphotoelectric detectors in the photoelectric detector layer.
 21. Themethod as claimed in claim 16, further comprising: forming ananti-reflection layer before forming the color filter layer.
 22. Themethod as claimed in claim 16, wherein the insulating material has arefractive index different from a refractive index of the photoelectricdetector layer.
 23. The method as claimed in claim 22, furthercomprising: forming a polysilicon layer inside the at least one trench.24. The method as claimed in claim 16, wherein the microlensescorrespond to the white filter and at least one of the red filter, greenfilter, or blue filter, respectively.
 25. The method as claimed in claim20, wherein the white filter and at least one of the red filter, greenfilter, and blue filter correspond to the photoelectric detectors,respectively. 26.-30. (canceled)